Lithographer



nitrl Leem Panni No. 80,461, dated .my 28, 186s.

faire geirrit- @ffi IMPROVEMENT IN STEAM SAFETY-VALVES.

dit Sdgebnle rentrer tu in' ilgese rttrrs @sind mit making graft ai tige sami.

TO ALL WHOM IT MAY CONCERN:

Be it known that I, OWEN R. DAVIS, of Lewistown, in the county of Miilin, and in the State of Pennsyl- Vania, have invented certain vnew and useful Improvements in Automatic Safety-Valves for Steam-Boilers; and do hereby declare that'the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, rind to the letters of reference marked thereon. p

The nature of my invention consists in the construction of a safety-valve, arranged on top of the boiler or dome, for the purpose of relieving,` any undue pressure of steam on the boiler, and which valve is so arranged that it is not liabletc lock itself by reason of deposit of sediment ut the valve-seat, whilstthe engineer may use the same at will to blow off steam. 1

In o'rder to enable others'skilled in the art 'to make and use my invention, I will now proceed to describe its construction and operation.

In the annexed drawings, forming part of this specification- A represents thc boiler, and Bthe dome on top thereof.

The top of the dome B is provided with two holes, one of which is covered by the valvea on top, and the other closed by the valve F from below.

The valve a is provided with a valve-stem, b, at the lower end of which, in the dome, -a. weight, C, is hung, which is sufficient to keep the valve'in its place until the boiler has generated steam enough to raise the same.

The upper 'end of the valve-stem b, above the dome, extends into the swivel or socket-end c, on the rod d, which extends upwards, and works up and down in the passage i. v s i This passage is constructed in the frame G, which is placed on top of the dome B, and the rod d, already mentioned, passes out through the top of said vframe, but the passage 'turns inward and leads into the chamber 0, so that when the valve a is raised by the pressure of the steam, the steam will pass upward andinto said chamber.

The piston-head D, which fits steam-tight into the chamber O, will, by the action of the steam, be pressed downward, as the entrance for the steam is abovehsaid piston-head, and the piston-rod E, which is secured under the centre of the same, rests on the valve F, already mentioned as closing'tbe centre hole in the top of the dome B, opening the same, and allow-ing the surplus-steam to escape through the same, and o ut through the frame G. i 1

As soon as the boiler by this means is relieved from the surplus pressure of steam, the valve a falls back in its seat, and any steam remaining in the chamber O escapes through the vent lc in the top of the same, thus allowing the steam in the boiler to press the valve F un in its place again, and,at the same time moving 'thet piston-head D up into the chamber O.

The piston-head must be so constructed thatits arca is larger than that of the valve F, else the pressure of the steam in the boiler on said valve would counteract the pressure of the steam in the chamber and on the piston-head, and.l the valve would not be opened whenthe valve a is raised, and the steam passes into the said chamber.

pressure in the boiler to ilo so.

The springfis merely placed under thc valve F, to holdthe same and the piston up when there is no At the upper end of the rod .cl are two set-rings, e c, the lower one of which comes down on topoi` the valve-case or frame G, and as the lower socket-end c of said rod is lbored out suiciently to let the upper end of the valve-stem b freely play up and down, it allows the steam in the boiler to raise the valve a without moving the rod d.

On top of the frame G is a lever, H, pivotod, one end of which is forked, and extends around the rod d, between the set-rings e e, and the other end extends to the side of the boiler, where arod, I, is attached to the same. Said rod extends downwards, and is, by means of a set-ring, L, hooked on the brace g, so that if the engineer desires to relieve the boiler of any steam, or carry less pressure, all he has to do is to pull the rod i out of the brace g, and hanga weight lto the end of saitl rod ortho-1d it dowmand the other end of the lever H will raise the rod d, and consequently the valve a, so that the steam will escape the sanie as if the valve had been raised by the pressure of 'the steam in the boiler. Y

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-` 1. The passage communicating with the chamber O, in combination. with the piston-head D, piston-rod E, and valve F, whereby to allow the steam to force said valve ,downwarianl relieve the boiler of any undue pressure of steam that may accumulate in it, substantially as herein set forth.

2. The arrangement of the piston-head D, piston-rod E, 'valve F, and case or frame G, whereby to prevent tampering with the valve Awhen onee arranged for the pressure required, substantially/as herein set forth.

- 3. The arrangement of the chamber O, passage z', valve-rod d, valve a, vent c, and weight C, substantially as set forth. l y

In testimony that I claim the foregoing, I have hereunto set my hand, this 23d day of. May,1868.

" 1 "ont DAVIS.

Witnesses:

C. M. ALEXANDER, LEOPOLD Evnn'r. 

